let n12: String = "我是一个好学生";
let ne: number = 23;
n12 = "33366666666666";
const gls7: String = "我是一个好学生";

let g1: boolean = false;
g1 = false;
let g2: number = 5;
let lis: number[] = [1, 2, 2, 3, 3,];
let list78: Array<number> = [1, 2];
let u78: undefined = undefined;
let u3: null = null;
let add: object = {
	"ad": 4, "name": "郭龙松", "fd": "fds"
}
const ff: object = {
	"ad": 4, "name": "郭龙松", "ear": "dsfsfs",
}
function add1(x: number, y: number, r?: number): number {
	return x + y;
}

let myAdd1 = function (x: number, y: number): number { return x + y; };

console.log(add1(1, 3, 4));

function add2(x: string, y: string): string {
	return x + y;
}
console.log(add2("sdfs", "sdf"));

function add3(x: String, y: String, r?：String): String {
	if (r) {
		return x + y + r;
	}
}
return x + y;
}


function adde(x: string | number, ...y: string[]) {
	return x + "" + y.join("| ");
}
adde("jdsfs", "sdfsd", "dsfs");
function addr(x: string | number, y: string | number) {
	if (typeof x === "string" && typeof y === "string") {
		return x + y;
	}
	else {
		return x;
	}

}